1. Field of the Invention
This invention generally relates to a liquid flow air treatment device. In a preferred embodiment, more specifically, the invention relates to a highly effective liquid flow air purification device that can be easily installed, on a retrofit basis, on many existing air handling units, and to air handling units provided with such an air purification device.
2. Prior Art
Interior spaces of buildings are typically supplied with automatically controlled temperatures using one or more air handling units that furnish a recirculating flow of air drawn out of the conditioned space, flowed through the air handling unit by an air blower therein, heated or cooled as necessary within the unit, and then flowed back into the conditioned space. In addition to supplying the desired temperature control within the conditioned space, air handing units of this general type may also be provided with the capability of purifying, at least to some extent, air flowing through the units.
The most common device used for this air purification task is the familiar replaceable flow-through air filter element that is disposed within the unit cabinet structure in the path of air being forced therethrough on its way back to the conditioned space served by the unit. Filters of this type are typically formed from a matted fibrous material (such as fiberglass) that serves to trap particulate matter, such as dust, borne in the air entering the unit. Additionally, electrostatic air filters are often incorporated in air handling units and provide improved particulate removal performance due to their electrostatic attraction and trapping of particulates substantially smaller than that which the ordinary fibrous filter can effectively capture.
However, as is well known, undesirable air pollutants are present in a variety of forms other than the relatively easy to capture particulates that the fibrous and electrostatic filter structures are designed to remove from the recirculated air. Another known type of air purification process is the use of a liquid spray, typically a water-based spray, directed against a filter element through which air to be supplied to a conditioned space is flowed. The liquid spray is maintained in continuous contact with the flowing air traversing the filter element, and, depending on the type of air purification system in which it is incorporated, serves to entrain a variety of airborne particulates as well as other types of pollutants such as aerosols, nitrogen oxides, sulfur oxides, carbon dioxides and monoxides, hydrogen sulfides and hydrocarbons. The liquid can then be drained away carrying entrained pollutants with it. This general type of air purification system also desirably serves to humidify the air delivered to the conditioned space.
These prior art air purification devices are suitable for many purposes. Typically, however, these prior art devices are not one hundred percent effective, and thus are not well suited for some important applications. For example, these devices may be inadequate to protect the occupants of a building from an intentional biological attack, where extremely toxic bacteria, such as anthrax, are intentionally introduced into the air inside the building. Also, these prior art devices, in their conventional form, may not provide the desired sterilization for surgical and other environments that require extremely clean air. Moreover, many of the prior art devices are relatively expensive or require relatively expensive maintenance. In addition, these types of systems are designed for smaller applications; not office buildings (air volume).
An object of the present invention is to provide a very simple, yet highly effective liquid spray air treatment device.
Another object of this invention is to provide a very simple and inexpensive method for retrofitting many existing air handling units to include an extremely effective air purification device.
A further object of the invention is to provide an air handling unit with a very simple and highly effective liquid flow air purification system.
A further object of the invention is to deliver a chlorinated solution onto a plate-fin cooling coil of an air handling unit to kill bacteria as air passes over the surface of the cooling coil fins.
Another object of this invention is to provide a control system for an air purification device in an air handling unit that automatically monitors and controls operation of the air purification device.
These and other objectives are attained with an air handling unit having a unique air treatment device, and a method for retrofitting existing air handling units to include the air treatment device. The air handling unit comprises a casing defining a space for conditioning air, and forming an inlet and an outlet; a cooling coil located inside the casing for cooling air therein; a sump located below the cooling unit for collecting liquid condensate on the cooling coil; and a supply air blower for drawing air into the casing, through the inlet, and forcing air through the cooling coil and outward through the outlet. The air handling unit further comprises a spray header secured inside the casing, adjacent to the cooling coil; and a pumping system connected to the sump and to the spray header for drawing chlorinated liquid solution from the sump and pumping the solution to and through the spray header, wherein the spray header sprays the solution onto the cooling coil and the solution flows downward over the cooling coil and into the sump below, and the solution treats the air passing over the surface of the cooling coils.
In a preferred embodiment, the liquid solution is an anti-bacteria solution, and the solution kills bacteria in the air forced through the cooling coil. Also, in this preferred embodiment, the cooling coil is of the plate-fin typexe2x80x94that is, the coil is comprised of a serpentine shaped coil extending between two parallel end plates or supports, with a series of thin, parallel fins pr plates mounted on the coil, and for example, these fins may be spaced apart from xe2x85x9 inch to {fraction (3/32)} inch. With these features, the spray header and the cooling coil may be used to develop and to maintain continuously a liquid flow filter that forces contact between the liquid flow and even extremely small particulates in the air stream. As a result, the liquid spray air treatment device is able to kill even extremely small bacteria such as anthrax.
Further benefits and advantages of the invention will become apparent from a consideration of the following detailed description, given with reference to the accompanying drawings, which specify and show preferred embodiments of the invention.